The present invention relates generally to a welding-type apparatus and, more particularly, to controlling an auxiliary power output of an engine driven welding-type apparatus according to engine operational parameters.
Engine driven welding-type apparatus and welding-type power supplies typically include a generator powered by the engine and configured to generate both welding-type power and auxiliary power. Direct current (DC) generators or alternating current (AC) generators are available depending upon a desired application. In either case, the welding-type apparatus generally includes output rectifiers to provide a relatively precise DC output power or filtering devices to provide relatively consistent AC output power to a welding-type output of the welding-type apparatus. Accordingly, relatively precisely controlled and accurate power is delivered to the welding-type output to effectuate a desired welding-type process.
Many generator-driven welding-type power supplies include an auxiliary output in addition to the welding-type output. As such, the welding-type apparatus is often configured to provide a 110 Volt (V) AC, 240 VAC, or 480 VAC, single or three phase, auxiliary power to the auxiliary output. Understandably, other power signals can be provided depending on the requirements of a particular device intended to be powered by the auxiliary power output. The auxiliary output is typically designed to provide power to additional worksite equipment such as hand power tools, lights, and the like. These devices, which are generally designed to be powered from transmission power receptacles, require a voltage supply that is generally constant regardless of current draw. Additionally, the power signal provided at these auxiliary outputs is, in part, dependent on engine operational parameters. That is, when an engine configured to power an auxiliary outlet is operated at an idle speed, the power signal provided to the auxiliary output is lower than the power signal provided to the same auxiliary outlet when the engine is operated at a speed above idle. If the auxiliary outlet has a load placed upon it when the engine is running at a speed below the speed required to generate the desired output, the draw at the auxiliary outlet can detrimentally effect engine operation and may damage the load if proper voltage and frequency are not attained.
Other engine driven generator apparatus have resolved this problem by not supplying any power to the auxiliary outlets unless the engine is operated at full speed. Although this solution resolves the condition of “overloading” the engine at idle speeds, it is inefficient in overall usage of the total power generated by the welding-type power source. That is, in many welding-type power source systems, when the engine is operated at full speed, it is capable of providing adequate power output to both the welding-type output and the auxiliary outputs of the apparatus. As such, running the engine at full speed consumes more fuel, generates more engine noise, and increases wear on the engine as compared to running the engine at a lower speed that is adequate to generate the desired electrical output.
Other welding-type power sources control the amount of power available at the auxiliary output based on a worst case engine output to ensure a load can be picked up from idle. That is, these systems do not utilize the entire range of power capable of being generated by an engine of the apparatus. During operation of the engine, a torque is generated that rotates the rotor of the generator relative to the stator thereby generating electrical power. The engine is capable of generating a peak horsepower which, generally speaking, is not coincident with a peak torque generated by the engine. This relationship often results in a particular generator being associated with a specific engine such that the engine operates at the horsepower rating coinciding with the peak torque value during maximum generator output. This association underutilizes the engine in that the engine is operated below the engine's peak horsepower. As such, the maximum power achievable by the engine of the power source is not utilized during standard operation of the engine driven generator apparatus.
Operation of engine driven welding-type apparatus can be shown by a power versus torque or power versus engine speed curve 2, as illustrated in FIG. 1. That is, as the engine speed or related torque of the engine increases, total power delivery including power delivery to an auxiliary output also increases. The increase in the power generated by the engine/generator combination increases until a threshold commonly referred to as power-torque knee 4 is reached. That is, when engine speed increases past the power-torque knee 4, torque decreases while horsepower continues to increase. Known welding type devices limit the operation of the engine driven generator assembly to points of operation approximately to the power-torque knee at full engine speed. Such a construction prevents the engine of such systems from operating at a maximum horsepower of the engine. Accordingly, a more robust engine is required to be associated with a corresponding generator. As such, the association, or rating, of a generator to an engine increases the size of the engine required to power a particular generator. The rating of the generator and engine increases the size and mass of the resulting combination and inefficiently utilizes the range of power cable of being generated by the engine.
It would therefore be desirable to have a system and method capable of controlling an auxiliary output of an engine driven welding-type apparatus based on operational parameters of the engine.